I just installed 24.04. My Grub does not show the other OSs installed on other drives (18.04 & 20.04). In the past I sort of remembering the Grub fixing itself. Maybe I don’t remember correctly. Anyway, comparing the Grubs, I now see an option for OS PROBER, My thinking is that I need to enable OS PROBER, Change TIMEOUT_STYLE to menu, and TIMEOUT from 0 to something bigger. Is this the correct action? Do I need to comment out OS PROBER once I get the correct Grub?
https://help.ubuntu.com/community/Grub2/Setup
enumerates and explains /etc/default/grub
parameters
No, you don't. They say "This entry is used to prevent GRUB from adding the results of os-prober to the menu... during execution of the update-grub command". And update-grub
is automatically executed after each kernel update, for instance.
So I have Virtual Box installed on my other two systems. The cautionary message in the Grub makes me cautionary in enabling OS Prober. Are any of the OSes at danger of damage?
"# If your computer has multiple operating systems installed, then you
probably want to run os-prober. However, if your computer is a host
for guest OSes installed via LVM or raw disk devices, running
os-prober can cause damage to those guest OSes as it mounts
filesystems to look for things.
#GRUB_DISABLE_OS_PROBER=false"
I can not claim anything for certain. At the same time I've read that os prober is considered insecure because it allows to bypass UEFI and access foreign filesystems. I.e. os prober is disabled due to these security reasons and not because it damages other OS'es drives.
reads
‘GRUB_DISABLE_OS_PROBER’
The grub-mkconfig
has a feature to use the external os-prober
program to discover other operating systems installed on the same machine and generate appropriate menu entries for them. It is disabled by default since automatic and silent execution of os-prober
, and creating boot entries based on that data, is a potential attack vector. Set this option to ‘false’ to enable this feature in the grub-mkconfig
command.
Removing the # from#GRUB_DISABLE_OS_PROBER=false"
and running update grub fixed the issue. With all the cautionary notes about OS_PROBER, I put the # back in and updated grub again. Interestingly, OS_PROBER still was executed when updating Grub.
LVM stands for logical volume management; if you dont know what it is - then you probably arent using it. The storage used for a VM in VirtualBox is usually backed by an ordinary file on your host - so it wont be affected by os-prober.
That is because you left the "#" at the start of your
If you did NOT want the prober to run, you had to use
GRUB_DISABLE_OS_PROBER=true